What's all this about using Nitrogen to inflate car tyres? I was having a chinwag with my merry postman, although he's not too merry about all the road works going on, making his job 3 times as hard. Reckons he bought 2 Avon car tyres for his old Punto, and they inflated them with gas instead of air - and stuck another couple of squid on the bill.
Another con?
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For the average motorist,YES!
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Nitrogen is supposed to permeate rubber more slowly than air, so the tyres stay inflated longer.
If that is true, then tyres in use will already contain mostly nitrogen because the other gases will have leaked out.
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>> If that is true, then tyres in use will already contain mostly nitrogen because the other gases will have leaked out.
Making them 22% under-inflated. You'd have to top them back up with air quite a few times but would probably still never achieve 100% nitrogen.
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>>Making them 22% under-inflated. You'd have to top them back up with air quite a few times but would probably still never achieve 100% nitrogen.
Air is 78% Nitrogen, as you know. So the first time the car is 22% other air. Lets assume that it leaks out, so you replace that 22% with air, so now the car is 95% nitrogen.
But they reckon that 100% nitrogen is better? Perhaps mathematically, but in the real world? I doubt it. And how do they suck out the air that's already in there?
Nitrogen is used in tyres such as those on airplanes and racing cars to avoid the moisture content. Nothing to do with loss of pressure.
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>> Nitrogen is used in tyres such as those on airplanes and racing cars to avoid
>> the moisture content. Nothing to do with loss of pressure.
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Being inert is the big point, should something occur on landing it helps reduces the chance of fire, say if the fuseable plus go. Normally they wear out quickly enough for corrosion not to be an issue.
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>> Lets assume that it leaks out, so you replace that 22% with air,
>> so now the car is 95% nitrogen.
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Which funily enough is exactly the figure ATS recommend as the minimum desirable nitrogen level.
"to get the maximum benefit you need to keep the nitrogen content above 95%,"
And from an American website advocating nitrogen inflatioon:
"In fact, with a nitrogen purity above 93.4%? in passenger tires, oxygen actually begins to migrate back into the tire. You can get all the benefits of nitrogen with a purity level between 93-98%. "
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>>. You'd have to top them back up with air quite a few times but would probably still never achieve 100% nitrogen.
This is the other question Dave the post asked. Thanks for the replies, I'll have to send him the link to this thread, and we might even get another victim on the forum :)
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Formula 1 tyres, for example, can run at 100 degrees C or more so they don't want water in the tyres such as might condense from compressed air. Drops of water vapourising will have some effect on pressure beyond the effect of temperature on the gases.
Perhaps the same applies to aeroplanes - I imagine it does, as the tyres appear to get hot enough to pop on occasion even without the sudden appearance of steam.
Not a problem for we ordinary folk.
Howsomever - if you last adjusted your tyre pressures when it was around freezing, and you check them today, you might find them 3-4 psi higher than you set them at e.g. for a tyre set to 30psi - whether or not you blew them up with nitrogen -
294/273*(30+15)-15 = 33.5
assuming temperature increase from 0C to 21C. E&OE, I'm not a real physicist.
Last edited by: Manatee on Wed 15 Apr 15 at 13:51
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>> if you last adjusted your tyre pressures when it was around freezing, and you check them today, you might find them 3-4 psi higher than you set them at e.g. for a tyre set to 30psi
[makes note to check tyre pressures!]
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Someone told me years ago that Michelin tyres were very good for maintaining their pressure and I did find that the Michelin's on my Mercedes, filled with nitrogen from Costco, absolutely never budged their pressures.
I've replaced them with Kumho All Season tyres, filled with air, and for months they needed topping up every time I checked them. They seem to have settled down now, so perhaps there's something in it that all that's left is the nitrogen?
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My experience too, BP, to the extent that when one of the Volvo's kept losing a small but measurable amount, I knew something was up. Tyre turned out to be fine, but imperfectly sealed against the rim. Smear of white stuff (and fifteen quid) and all was well.
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I had a puzzling slow puncture after a puncture repair. It was a duff valve core fitted after the repair. Found with soapy water.
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>> I had a puzzling slow puncture after a puncture repair. It was a duff valve
>> core fitted after the repair. Found with soapy water.
That was the free air trying to get in
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>> Another con?
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Well, you are paying for incomplete air which was free when it was complete. :-)
Last edited by: Old Navy on Wed 15 Apr 15 at 16:49
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Like those sharks who sell you milk with the cream skimmed off, then sell you the cream in a separate pot, ON?
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Possibly, but the milk was not free before they whipped the cream off it.
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Nitrogen inflation (gas going up) :) - jc2
